A PDP is formed by injecting gas into a cell between two substrates comprising transparent electrodes each having a predetermined pattern. When a discharge voltage is applied to the cell where the gas is injected and sealed, a fluorescent substance is excited by ultraviolet rays generated from the discharge voltage to embody figures, letters or graphic.
FIG. 1 is an exploded perspective view illustrating a structure of a general PDP.
In the general PDP, a front substrate 10 where a electrode X (sustain electrode) and a electrode Y (scan electrode) are formed and a rear substrate 20 where an address electrode is formed are sealed at a predetermined distance in parallel.
The electrodes X and Y in the front substrate 10 sustain radiation generated by discharge in the cell selected at an address period. The electrodes X and Y are formed of transparent electrode (or ITO electrode) Xa and Ya that are made by transparent ITO materials and of bus electrodes Xb and Yb that are made by metal materials. The electrodes X and Y are covered by a dielectric layer 12 for limiting discharge current and insulating the electrodes. A protective film 13 such as a MgO film is formed on the dielectric layer 12.
The rear substrate 20 comprises barriers 21 arranged in parallel as a stripe type (or dot type) for forming cells C which are discharge spaces. Also, the rear substrate 20 comprises address electrodes A arranged in parallel with the barrier 21 and crossed with the electrodes X and Y. A dielectric layer 23 is formed on the address electrode A. Then, a R.G.B fluorescent layer 24 for emitting visible rays at address discharge to display image is coated on the upper surface of the rear substrate 20 except the top surface of the barrier 21.
For charging discharge gas in the above-described PDP, a sealing unit 27 is formed between the front substrate 10 and the rear substrate 20 so as to maintain airtightness between the front substrate 10 and the rear substrate 20. Then, vacuum exhaust is performed on the inside of the PDP, and discharge gas is charged in the vacuum-exhausted space.
As shown in FIG. 2, an exhaust hole 25 is formed on the rear substrate 20. Next, the rear substrate 20 and an exhaust small tube 26 are seamed using the sealing unit 27, so that the exhaust small tube 26 is safely positioned on the exhaust hole 25. As a result, gas exhaust and discharge gas injection in the panel are performed through the exhaust small tube 26.
However, in the conventional PDP, the exhaust hole 25 is located at the outside of the display area. Although the location of the exhaust hole 25 does not matter in case of the PDP consisting of a single panel, there is a limit in reduction of a seam between panels when a multi-PDP comprising a plurality of PDP panels for a large screen is embodied. That is, when the exhaust hole 25 is formed at the outside of the display area, the seam of the indefinite extension multi-PDP cannot be reduced to less than several cms in consideration of precision of the location of the exhaust hole 25 and the diameter of the exhaust small tube 26.